1. Field of the Invention
The present invention relates to USB connectors and more particularly, to a USB connector, which has the fixed terminals and springy terminals arranged in four rows inserted through eighteen through holes of a circuit board that are arranged in four rows in such a manner that the first row and the last row each include five through holes and the other two rows each include four through holes. Subject to this arrangement, one USB 3.0 connector and one USB 2.0 can be selectively installed in one common circuit board.
2. Description of the Related Art
Following fast development of modern electronic technology, many different advanced and small-sized electronic devices have been intensively used in our daily life. Nowadays, many people use notebook computer instead of desk computer for the advantage of high mobility. Further, different transmission cables are used for data transmission among different electronic devices. Serial transmission connectors, such as USB (Universal Serial Bus) connectors are intensively used in different electronic devices.
An early design of USB 1.1 connector provides a transmission speed of 1.5 Mbit/s. The invention of USB 2.0 connector improves the transmission speed up to 480 Mbit/s. This design can simply be used in a peripheral apparatus (such as card reader, printer, memory stick, network phone and network camera) of low driving power. Nowadays, these data transmission speeds cannot satisfy the demand for quick transmission of a big amount of data within a limited time, i.e., USB 2.0 cannot be used with a high capacity hard disk drive or DVD copier, DVD player or any advanced blue light electronic device. In consequence, high speed data transmission connectors have been continuously created. For example, USB 3.0 provides a transmission speed as high as 5 Gbit/s. In consideration of compatibility to conventional USB 1.1 or 2.0, USB 3.0 maintains the original metal terminals and adds an extra set of metal terminals, i.e. a USB 3.0 connector has two sets of metal terminals arranged therein. These two sets of metal terminals are separately made from two different metal sheets by a stamping technique and separately bent into shape. After preparation of the two different sets of metal terminals, they are put in an insert-molding mold and molded in an electrically insulative housing. After molding, a metal shield is secured around the periphery of the electrically insulative housing, and a USB 3.0 connector is thus obtained.
FIGS. 11 and 12 illustrate conventional double-stacked USB 3.0 connectors. According to these designs, there are 5 USB 3.0 fixed terminals and 4 USB 2.0 springy terminals respectively positioned in each of the first connection port and the second connection port. The rear bonding end pieces of all the fixed terminals and springy terminals that are respectively bonded to a circuit board are arranged in four rows in such an order from the front side toward the rear side that 4 terminals in one row and 5 terminals in a next row. However, the arrangement of the two rows of USB 3.0 fixed terminals causes the pitch of the USB 2.0 springy terminals to be increased (3.2 mm). Thus, a circuit board designed for the installation of a USB 3.0 connector is not suitable for the installation of a USB 2.0 connector (the terminal pitch of a USB 2.0 connector is 2.63 mm). In consequence, two different designs of circuit boards having different circuit layouts must be prepared for USB 2.0 connector and USB 3.0 connector separately, increasing the cost.
Therefore, it is desirable to provide a USB 3.0 connector, which can be installed in a circuit board for USB 2.0 connector.